1 Try this: Cozy in cotton or warm in wool? Sat Aug 02, 2014 9:21 am
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Admin
Try this: Cozy in cotton or warm in wool? Which do you think will keep you warmer; wearing one woollen jumper, or putting on four cotton t-shirts? This experiment might help you to decide. Safety: This experiment uses hot water. Take care whenever pouring or touching an object containing hot water. Younger readers must have an adult to help. Be aware that opened cans sometimes have sharp edges. You will need
What to do
What's happening? Any material that helps slow energy from moving from one place to another is called an 'insulator'. Heat is a form of energy which describes how much particles jiggle about. Particles that are close together, like in solids, can pass heat easily by bumping into colder particles. This is called 'conduction'. Particles spread far apart, like in gases such as air, don't pass or conduct heat easily. Think about it this way – is it easier to bump into another person on a crowded bus, or on a soccer pitch in the middle of a game? Woollen jumpers keep you warm by holding the air in between its fibres close to your body. Since air doesn't conduct heat easily, the heat stays close to you rather than drifting away. The more air you trap, the warmer you'll be. Birds fluff their feathers to ward off the chill for this very reason. Layers of cotton will trap more air between them than a woollen jumper; more layers equals more warmth. Earth's atmosphere – a big layer of air – also traps heat. Imagine how cold we'd be if that disappeared! Try other materials and see which ones work the best at insulating. |